As part of a broad program of research on sleep physiology, the following studies have been recently completed or are in progress: a) Reptiles show large amplitude spike potentials from several brain areas during behavioral sleep. These potentials resemble in their waveform and temporal distribution the spike potentials recorded from the ventral hippocampus of cats and rats during NREM sleep. Studies in progress aim to strengthen the analogy between the reptilian and mammalian spikes by comparing the response of both to amphetamine, barbiturates, PCPA, and AMPT. Other studies aim to determine which inputs to the hippocampus control the appearance of the spike. b) Earlier studies have shown that sleep time and metabolic rate are correlated across species. A study in progress evaluates whether sleep is responsivve to changes in metabolic rate in individual animals by administering thyroxine to rats and noting changes in sleep parameters. c) An automatic system for the scoring of rat sleep is being developed. This system is based upon EEG and EMG amplitude comparisons using inexpensive resetting integrators. Scoring will be possible by counting integrator resets or by a laboratory computer. The system is being validated against scoring by behavioral observation and visual inspection of polygraphic recordings. BIBLIOGRPAHIC REFERENCES: Litchman, J., & Rechtschaffen, A. Mentalis EMG activity associated with sleep stages, cycles, and body movements. In M.H. Chase, M.M. Mitler, & P.L. Walter (Eds.), Sleep research. Vol. 5. Los Angeles: Brain Information Service/Brain Research Institute, UCLA, 1976. p. 148. Metz, J., & Rechtschaffen, A. Hippocampus spikes during sleep in rats. In M.H. Chase, M.M.Mitler, & P.L. Walter (Eds.), Sleep research. Vol. 5. Los Angeles: Brain Information Service/ Brain Research Institute, UCLA, 1976. p. 28.